Non-corrosive reinforcing member having bendable flanges

ABSTRACT

Non-corrosive concrete reinforcing members are formed by pultruding reinforcing fibers through resin to produce an elongated core and a plurality of elongated flanges extending radially outward from the core. A slot is formed through a portion of the elongated core such that each flange has a free inner edge adjacent the slot. The reinforcing member is thereby bendable along the slot in a direction transverse to the elongated core.

FIELD OF THE INVENTION

The present invention relates generally to reinforced composite articlesand, more particularly, to reinforced composite articles forstrengthening concrete.

BACKGROUND OF THE INVENTION

Concrete and other masonry or cementitious materials have highcompressive strength, but relatively low tensile strength. When concreteis employed as a structural member, such as in a building, bridge, pipe,pier, culvert, or the like, it is conventional to incorporatereinforcing members to enhance the tensile strength of the structure.Historically, the reinforcing members are steel or other metalreinforcing rods or bars, i.e., "rebar". Such reinforcing members may beplaced under tension to form prestressed concrete structures.

Although steel and other metals can enhance the tensile strength of aconcrete structure, they are susceptible to oxidation. For example,ferrous metal rusts by the oxidation thereof to the corresponding oxidesand hydroxides of iron by atmospheric oxygen in the presence of water.When it is poured, concrete is normally at a pH of 12 to 14 (i.e., athigh alkalinity) due to the presence of hydroxides of sodium, potassium,and calcium formed during the hydration of the concrete. As long as a pHin this range is maintained, steel within the concrete is passive, whichmay result in long-term stability and corrosion resistance.

Exposure to a strong acid, or otherwise lowering the pH of concrete, cancause steel contained in concrete to become corroded. For example,chlorine ions permeating into the concrete can cause corrosion. Sourcesof chlorine ions include road salt, salt air in marine environments, andsalt-contaminated aggregate (e.g., sand) used in making the concrete.When the reinforcing steel corrodes, it can expand and create internalstresses in the concrete. These internal stresses can lead to cracking,and ultimately disintegration, of the concrete. Moreover, cracking andcrumbling concrete may expose additional steel to atmospheric oxygen,water, and sources of chlorine ions.

Various solutions to the corrosion problem of steel rebar have beenoffered. Non-corrosive coatings on the concrete, the steel rebar, orboth have been proposed. For example, U.S. Pat. No. 5,271,193 to Olsenet al. proposes a steel-reinforced concrete product, such as a manholecover, having a coating of a corrosion-resistant gel coat layer and anintermediate layer of fiberglass between the concrete and the gel coatlayer. The gel coat layer is described as being a "hardenable polymericfluid material." U.S. Pat. No. 4,725,491 to Goldfein proposes steelrebar members having chemical conversion iron oxide coatings, such asblack iron oxide. U.S. Pat. No. 5,100,738 to Graf proposes steel rebarhaving an outer layer of a synthetic material (e.g., epoxy resin) and anintermediate layer of aluminum or aluminum alloy between the outer layerand the steel. Unfortunately, in general these exemplary coatings tendto be expensive and have received mixed results and acceptance.

There has also been interest in replacing steel with variousfiber-reinforced resins. For example, U.S. Pat. No. 5,580,642 to Okamotoet al. proposes a reinforcing member for civil and architecturalstructures made from a mixture of reinforcing fibers and thermoplasticfibers. U.S. Pat. No. 5,613,334 to Petrina proposes a non-metalliclaminated composite reinforcing rod for use in reinforced or prestressedconcrete. A corrosion-resistant fiber-reinforced rebar, disclosed inU.S. Pat. No. 5,650,109 to Kaiser et al. comprises a fiber reinforcedthermoset core and an outer cladding formed of sheet molding compound(SMC). These materials are formed into rebar through modified pultrusionprocesses.

Some rebar components are desirably curved or bent in order to followthe contour of the surrounding concrete structures. Unfortunately, rebarformed from fiber-reinforced resins may be difficult to bend in thefield without causing the rebar to crack or break. Forming non-lineararticles via pultrusion processes may also be troublesome. Becausepultrusion involves pulling material through an elongated heated diewhich at least partially cures, and therefore stiffens, the pultrudedarticle, establishing bends or curves in the articles withoutsacrificing the advantages provided by pultrusion may be problematic.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to providenon-corrosive reinforcing members for use within concrete structures.

It is also an object of the present invention to provide non-corrosivereinforcing members for use within concrete structures that provideincreased concrete strength.

It is another object of the present invention to provide non-corrosivereinforcing members that can be easily bent in the field withoutcracking or breaking.

These and other objects of the present invention are provided by anon-corrosive reinforcing member formed by pultruding reinforcing fibersthrough resin and having an elongated core, a plurality of elongatedflanges extending radially outward from the core, and a slot formedthrough a portion of the elongated core such that each flange has a freeinner edge adjacent the slot. The reinforcing member is thereby bendablealong the slot in a direction substantially transverse to the elongatedcore. The flanges are preferably equidistantly spaced around the core.Additionally, the outer edge of each flange is preferably parallel withthe longitudinal direction of the elongate core.

At least one of the flange faces may have a non-planar surface portionfor improving concrete adhesion thereto. The non-planar surface portionmay be added during or after pultrusion operations. In addition, theouter edge portion of a flange may be thicker than the other portions ofthe flange. The elongated core may also have the same or smallerthickness than a flange.

Each flange typically has a constant, thin cross section with a thickersection along its outer edge portion. A rod can have any number offlanges, but an even number (i.e., 4, 6, 8, etc.) is preferred. Inaddition, each flange preferably has a non-planar surface whichfacilitates concrete adhesion to the surface of each flange. Animportant aspect of the invention is that the elongated core has across-sectional dimension about the same (or less) as each flange.

Reinforcing members according to the present invention are designed tobe bent by hand by workers in the field and without the need for largeand complex bending tools. To facilitate bending, a slot is formed alongthe elongated core at locations where bends are desired. When thereinforcing member is bent, the flanges fold down on each other becauseof the unrestrained inner edge created by the slot. The reinforcingmember may be held in this position by various methods, such as by usingadhesive, by tying down, etc. Slots can be made either duringmanufacturing or later in the field.

Reinforcing members according to the present invention may be fabricatedby the following operations: impregnating reinforcing fibers bypultruding them through a bath of resin material; forming theimpregnated reinforcing fibers into an elongated core having a pluralityof elongated flanges extending radially outward therefrom, each flangehaving opposite faces terminating at an outer edge; and forming a slotthrough a portion of the elongated core such that each of the flangeshas a free inner edge adjacent the slot. The impregnated reinforcingfibers are preferably heated as they pass through a shaping die. Priorto full curing, portions of one or more flange faces may be embossed toprovide non-planar surface portions thereon for improving concreteadhesion.

According to another aspect of the present invention, a reinforcingmember has a central core member and a plurality of longitudinallyspaced-apart flanges. The central core member has a plurality ofradially spaced slots formed therein along the longitudinal directionthereof. Flanges are connected to the central core member via the slots.Because the flanges are longitudinally separated by gaps, thereinforcing member can be bent at any of these gaps, without the needfor slots formed within the central core member.

The present invention is advantageous because non-corrosive reinforcingmembers having the same cross-sectional area as round rebar can bemanufacturing with more surface area than the corresponding round rebar,with more strength. Furthermore, reinforcing members manufacturedaccording to the present invention, can be bent by hand in the field,thereby decreasing the time required to install the reinforcing membersprior to pouring concrete.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of four-flanged reinforcing member according toone embodiment of the present invention.

FIG. 2 is a cross-sectional view of the reinforcing member of FIG. 1,taken along lines 2--2.

FIG. 3A is a cross-sectional view of a four-flanged reinforcing memberhaving a smaller central core than the reinforcing member of FIG. 2.

FIG. 3B is a cross-sectional view of the four-flanged reinforcing memberof FIG. 2 having enlarged flange edge portions

FIG. 4 is a perspective view of the four-flange reinforcing member ofFIG. 1 having a slot formed through a portion of the central core.

FIG. 5 is a cross-sectional view of a six-flanged reinforcing memberaccording to another embodiment of the present invention.

FIG. 6 is a side view of the four-flanged reinforcing member of FIG. 1illustrating crimped or embossed edge portions of each flange.

FIG. 7 illustrates a sinusoidal pattern for flange edge portionsaccording to an embodiment of the present invention.

FIG. 8 is a cross-sectional view of the four-flanged reinforcing memberof FIG. 4 taken along lines 8--8 and illustrating a bending slot betweeneach flange and the reinforcing member core.

FIG. 9 is a side view of a four-flanged reinforcing member about to bebent about a bending slot between each flange and the reinforcing membercore.

FIG. 10 is a side view of four-flanged reinforcing member according tothe present invention bent about 90°.

FIG. 11 is a cross-sectional view of the reinforcing member of FIG. 10taken along lines 11--11.

FIG. 12 is a side view of the bent four-flanged reinforcing member ofFIG. 10 embedded in concrete.

FIG. 13A is a perspective view of a reinforcing member having a centralcore with flanges connected thereto, according to an aspect of thepresent invention.

FIG. 13B is an exploded cross-sectional view of the reinforcing memberof FIG. 13A.

FIG. 14A is a perspective view of a reinforcing member having a centralcore with flanges connected thereto and with gaps therebetween,according to an aspect of the present invention.

FIG. 14B illustrates the reinforcing member of FIG. 14A being bent atone of the gaps between the flanges.

FIG. 15 schematically illustrates operations for manufacturing compositereinforcing member according to the present invention.

FIG. 16 illustrates an apparatus for fabricating composite reinforcingmember according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

Referring now to FIGS. 1 and 2, a non-corrosive, composite reinforcingmember 10 formed from reinforcing fibers and curable resin material,according to an embodiment of the present invention, is illustrated. Theillustrated reinforcing member 10 includes an elongated core 12 having aplurality of elongated flanges 14 extending radially outward therefrom.Each flange 14 has opposite faces 14a, 14b which terminate at an outeredge 15. The illustrated reinforcing member has four flanges 14 arrangedsubstantially equidistantly around the elongated core 12 to define across-section having a "cross-shaped" configuration.

However, it is to be understood that different numbers andconfigurations of flanges may be utilized without departing from thespirit and intent of the present invention. For example, referring toFIG. 5, a reinforcing member 11 according to another embodiment of thepresent invention may have six flanges 14 arranged around an elongatedcore 12 as illustrated. The present invention is not limited toreinforcing members having an even number of flanges or to flangesarranged equidistantly around a core.

Preferably, the reinforcing fibers in the reinforcing member 10 areunidirectional. Unidirectional fibers should be oriented to besubstantially parallel with the longitudinal direction of the elongatedcore 12. In this configuration, the fibers can enhance the tensile andflexural strength and rigidity of the reinforcing member 10. Inaddition, it is preferred that unidirectional fibers are located alongthe surface of each flange. By having fibers along the surface of aflange, contact can be made directly between the concrete and thefibers. Contact between the concrete and the fibers increases thestrength of the reinforcing member. Accordingly, the more fibers at thesurfaces of each flange, the stronger the reinforcing member is withinconcrete. A fibrous mat is also contemplated.

Referring now to FIG. 3A, another embodiment of the present invention isillustrated. The four-flanged reinforcing member 10' of FIG. 3A has asimilar configuration to the reinforcing member 10 illustrated in FIG.2. However, the elongated core 10' of reinforcing member 10' in FIG. 3Ahas a cross-sectional dimension less than or equal to a cross sectionaldimension of any of its respective flanges.

Preferably, the flanges of reinforcing members manufactured according tothe present invention have relatively thin cross-section dimensions(i.e., thickness). Listed below in Table 1 are exemplary cross-sectiondimensions for various sizes of flanges. Flange size is measured fromthe core of the reinforcing member to the outer edge of a flange (i.e.,the width of the flange).

                  TABLE 1    ______________________________________    Flange Width  Flange Thickness    ______________________________________    2.25 inches   0.098 inch    2.0 inches    0.075 inch    1.625 inches  0.060 inch    0.50 inch     0.050 inch    ______________________________________

The thin cross section of each flange creates a high modulus to volumeratio in plane with the width of each flange. Furthermore, reinforcingmembers having a flanged configuration according to the presentinvention have greater surface area than convention round rebar of thesame cross-sectional area. This is set forth in Table 2 below.

                  TABLE 2    ______________________________________           Size      Cross-Sect. Area                                   Surface Area    ______________________________________    Flanged  2.25" × 2.25"                         .44 in.sup.2  9.39 in.sup.2    Round    0.75" OD    .44 in.sup.2  2.36 in.sup.2    Flanged  2.0" × 2.0"                         .31 in.sup.2  8.3 in.sup.2    Round    0.625" OD   .31 in.sup.2  1.96 in.sup.2    Flanged  1.625" × 1.625"                         .25 in.sup.2  6.74 in.sup.2    Round    0.50" OD    .25 in.sup.2  1.57 in.sup.2    Flanged  0.50" × 0.50"                         .11 in.sup.2  4.2 in.sup.2    Round    0.375" OD   .11 in.sup.2  1.17 in.sup.2    ______________________________________

In contrast with round rebar, more surface area is available forconcrete to adhere to using flanged reinforcing members according to thepresent invention.

Referring now to FIG. 3B, another embodiment of the present invention isillustrated. The four-flanged reinforcing member 10" of FIG. 3B has asimilar configuration to the reinforcing member 10 illustrated in FIG.2. However, flange portions 17 adjacent the outer edges 15 of eachflange have a greater cross-sectional dimension (i.e., are thicker) thanthe remainder of each respective flange 14. By increasing the thicknessof a flange towards the outer edge thereof, there is provided additionalsurface area for concrete to adhere to, thus increasing the strength ofthe concrete. Flanges may have various thickness at various locationswithout departing from the spirit and intent of the present invention.

Referring now to FIG. 4, a slot 18 may formed through a portion of theelongated core 12 of the reinforcing member 10 such that each flange hasa free inner edge 19 adjacent the slot 18. FIG. 8 is a cross-sectionalview of the reinforcing member in FIG. 4 clearly showing that eachflange has a free inner edge 19 adjacent the slot 18. The slot 18 may beformed by cutting the elongated core 12 between each pair of adjacentflanges 14 using various known techniques. The slot 18 may be formedduring fabrication of the reinforcing member 10, immediately afterfabrication, or in the field prior to installation. It is to beunderstood, however, that the reinforcing member 10 need not have a slotformed through the elongated core 12. When there is no need to bend thereinforcing member, there is no need for a slot. Accordingly, straightsections of reinforcing members, according to the present invention, maybe utilized without having slots.

By forming a slot 18 in the elongated core 12, each flange has a freeinner edge 19 that is unrestrained when the reinforcing member 10 issubjected to bending forces. When the reinforcing member 10 is subjectedto bending forces, as illustrated in FIGS. 9 and 10, the flanges 14 folddown on each other and permit a portion of the reinforcing member to bebent in a direction transverse to the longitudinal direction of the core12. Because the flanges 14 are free to fold down, the reinforcing member10 has a generally flat configuration that allows it to be bent.

As shown in FIG. 11, the four-flanged reinforcing member 10 has two pairof folded flanges 14. Similarly for reinforcing member havingeven-numbered flanges, one-half of the total number of flanges will befolded together along one side of the reinforcing member and the otherhalf will be folded together along the opposite side.

Reinforcing members according to the present invention may be bent byhand in the field without requiring the use of bending tools and thelike. The reinforcing member 10 can be held in a desired bentconfiguration by various methods known to those skilled in this art,including but not limited to, adhesives, wires ties, and the like. Slotscan be provided in various lengths and at various locations along theelongated core 12.

Referring now to FIG. 6, portions 20 of a flange 14 may have anon-planar surface as a result of crimping, embossing, and similaroperations. In FIG. 6, the outer edge portions 20 of each flange have agenerally crimped configuration near the outer edge 15 thereof. Thenon-planar flange surface increases adhesion of concrete to thereinforcing member flange 14. Flange strength is increased, as well.Those skilled in this art will appreciate that non-planar flangesurfaces can take any number of configurations known to those skilled inthis art to improve the mechanical bond between the reinforcing member10 and a surrounding concrete structure. For example, FIG. 7 illustratesa sinusoidal pattern for flange edge portions according to anotherembodiment of the present invention.

In addition, edge portions of each flange may be sprayed with additionalmaterial to form a non-planar surface thereon for improving concreteadhesion thereto. Various types of materials may be utilized, includingthermoplastic and thermosetting materials.

Referring now to FIG. 12, a reinforced structure 30 according to aspectsof the present invention is illustrated. The reinforced structure 30contains a reinforcing member 10 surrounded by a mass of cementitiousmaterial 32. Exemplary cementitious materials include Portland cement,as well as sand, water and aggregate mixtures. The reinforcing member 10is bent approximately 90° along the slot 18 to conform with the"L-shaped" reinforced structure 30.

Referring now to FIGS. 13A-13B, a reinforcing member 35 having a centralcore member 36 and a plurality of flanges 37, according to anotheraspect of the present invention, is illustrated. The central core member36 has a plurality of radially spaced slots 36a formed therein along thelongitudinal direction thereof, as illustrated. These slots 36a serve asmeans for removably securing a plurality of flanges to the central coremember 36. Various methods of securing the flanges 37 within the slots36a, may be utilized without departing from the spirit and intent of thepresent invention. For example, the flanges 37 may snap or slide intothe slots 36a, or may be held therein via adhesives and the like.

The flanges 37 and central core member 36 may be fabricatedindependently of each other and via various methods, includingpultrusion methods described herein. Edge portions 37a of each flange 37may be embossed or sprayed with additional material to form a non-planarsurface thereon for improving concrete adhesion thereto.

It is to be understood that the present invention is not limited to theillustrated reinforcing member 35. The central core member 36 may havedifferent configurations and may allow for different numbers of flangesto be secured thereto. It is preferred that the central core member 36be formed of a thermoplastic material. Accordingly, heat can be added tothe central core member 36 to facilitate bending the reinforcing member35 to a desired configuration. When heat is removed, preferably thecentral core member 36 maintains its bent configuration. Accordingly,the need to secure the reinforcing member 35 in some manner to maintainthe bent configuration is eliminated. Alternatively, portions of theflanges 37 and/or the central core member 36 may be removed, such as bygrinding, to facilitate bending.

According to another aspect of the present invention, the central coremember 36 may be formed of flexible material that can be bent withoutthe need for heat. However, the central core member 36 may also beformed of other non-corrosive materials such as aluminum and polymericmaterials.

Referring now to FIGS. 14A-14B, a reinforcing member 38 having a centralcore member 39 and a plurality of longitudinally spaced-apart flanges40, according to another aspect of the present invention, isillustrated. The central core member 39 has a plurality of radiallyspaced slots 39a formed therein along the longitudinal directionthereof, as illustrated. These slots 39a serve as means for removablysecuring thereto a plurality of longitudinally spaced-apart flanges 40.As described above, various methods of securing the flanges 40 withinthe slots 39a, may be utilized without departing from the spirit andintent of the present invention. For example, the flanges may snap orslide into the slots 39a, or may be held therein via adhesives,mechanical anchors, and the like.

Because the flanges 40 are longitudinally separated to form gapstherebetween, the reinforcing member 38 can be bent at any of thesegaps, as illustrated in FIG. 14B. Accordingly, slots within the centralcore member 39 are not required for the reinforcing member to bend. Theflanges 40 do not fold down on themselves when the reinforcing member 38is bent. Accordingly, more flange surface area is available for contactwith concrete adjacent to each bend than with the slotted embodimentdescribed above and illustrated in FIG. 12.

Another advantage of the embodiment illustrated in FIGS. 14A-14B is thatreinforcing fibers are not exposed to corrosive environments. When aslot is formed within the central core member 12 of the reinforcingmember 10 illustrated in FIG. 4, reinforcing fibers may be exposed as aresult. When exposed to corrosive environments, these exposed fibers maydegrade in strength, which may, in turn, lead to strength degradation ofthe reinforcing member.

Still referring to FIGS. 14A-14B, the flanges 40 and central core 39 maybe fabricated independently of each other and via various methods,including pultrusion methods described herein. Edge portions 40a of eachflange 40 may be embossed or sprayed with additional material to form anon-planar surface thereon for improving concrete adhesion thereto.

It is to be understood that the present invention is not limited to theillustrated configuration of the reinforcing member 38. The central core39 may have different configurations and may allow for different numbersof flanges 40 to be secured thereto. It is preferred that the centralcore 39 be formed of a thermoplastic material. Accordingly, heat can beadded to the central core 36 to bend the reinforcing member 38 to adesired configuration. When heat is removed, preferably the central core39 maintains this configuration. Accordingly, the need to secure thereinforcing member in some manner to maintain the bent configuration iseliminated. According to another aspect of the present invention, thecentral core 39 may be formed of flexible material that can be bentwithout the need for heat, such as aluminum, polymeric materials, andthe like.

The present invention also anticipates that the flanges and/or centralcore of each reinforcing member embodiment described above may includevarious types of connectors for connecting multiple reinforcing memberstogether. Accordingly, multiple reinforcing members can be securedtogether to form various structures. Conventional rebar is often securedtogether via wire ties and the like, which can be rather laborintensive. The present invention allows multiple reinforcing members tobe assembled together quickly and easily, without the need forconventional securing methods.

Referring now to FIG. 15, operations for fabricating reinforcing membersaccording to the present invention are illustrated. In general,fabrication operations include: impregnating reinforcing fibers bypultruding the reinforcing fibers through a bath of resin material(Block 50); forming the impregnated reinforcing fibers into an elongatedcore having a plurality of elongated flanges extending radially outwardtherefrom (Block 60); embossing portions of one or more flange faces toprovide a non-planar surface portion thereon (Block 70); and forming aslot through a portion of the elongated core such that each of theflanges has a free inner edge adjacent the slot (Block 80).

Conventional pultrusion processes involve drawing a bundle ofreinforcing material (e.g., glass filaments or fibers) from a sourcethereof, wetting the fibers and impregnating them (preferably with athermosettable polymer resin) by passing the reinforcing materialthrough a resin bath in an open tank, pulling the resin-wetted andimpregnated bundle through a shaping die to align the fiber bundle andto manipulate it into the proper cross-sectional configuration, andcuring the resin in a die mold while maintaining tension on thefilaments. Because the fibers progress completely through the pultrusionprocess without being cut or chopped, the resulting products generallyhave exceptionally high tensile strength in the longitudinal (i.e., inthe direction the filaments are pulled) direction. Exemplary pultrusiontechniques are described in U.S. Pat. Nos. 3,793,108 to Goldsworthy;4,394,338 to Fuway; 4,445,957 to Harvey; and 5,174,844 to Tong, thedisclosures of which are incorporated herein by reference in theirentirety.

A particularly preferable apparatus for fabricating reinforcing membersaccording to the present invention is illustrated in FIG. 16. Theapparatus 110 includes a reinforcing fiber feed station 112, a shapingdie 114, and a finishing station 116.

Reinforcing Fiber Feed Station

The reinforcing fiber feed station 112 generally includes a reinforcingmaterial supply 118, a bath 120 of a thermosetting resin 127, a formingstation 122, and a preheating station 124. The illustrated reinforcingmaterial supply 118 includes multiple spools 119 of reinforcing fibers121 mounted within a creel 123. The creel 123 may include virtually anynumber of spools 119. Creels including 100 or more spools are common.Preferably, the reinforcing fibers 121 are drawn from the spools 119through a series of ceramic bushings (not shown) positioned at the frontof the creel 123 to maintain alignment and reduce breakage of thereinforcing fibers 121.

From the creel 123, the reinforcing fibers 121 are guided via a creelguide or card 125 to the bath 120 (shown in sectional view) of anunsaturated polyester resin or other thermosetting resin 127 such asvinyl ester resins, polyurethanes, epoxies, and phenolics. The creelguide 125 controls alignment to prevent twisting, knotting or any otherdamage to the reinforcing fibers 121. The reinforcing fibers 121 aredirected under an impregnating roll(s) or bar(s) 129 (i.e., a so-called"wet-out bar"), which submerges the reinforcing fibers in the bath 120and impregnates them. This type of bath is sometimes referred to as a"dip bath."

Alternatively, the reinforcing fibers 121 may be impregnated withthermosetting resin 127 via an apparatus that injects the thermosettingresin onto the reinforcing fibers. Such injection apparatus are known tothose skilled in the art, as are other means for impregnating thereinforcing fibers 121.

After impregnation, the impregnated fibers (designated 130 in FIG. 16)may be formed into a particular alignment at forming station 122, priorto entering the shaping die 114. A forming station 122 is preferablyincluded to ensure positive alignment of the impregnated reinforcingfibers 130 relative to the shaping die 114. As is known to those skilledin the art, various guide slots, holes, and clearances of the formingstation 122 must be sized to prevent excess tension on the wetreinforcing fibers, but also must permit sufficient resin removal toprevent viscous drag on the reinforcing fibers 130 at the entrance ofthe shaping die 114 from being too high.

After the forming station 122, the impregnated reinforcing fibers 130are preferably preheated prior to entering the shaping die 144 in asuitable heating unit 124. As is know to those skilled in the art,conventional ovens, as well as infrared, microwave, and radio frequencydevices may be utilized to preheat the impregnated reinforcing fibers130. Preferably, the impregnated reinforcing fibers 130 are uniformlyheated throughout their cross-section to reduce the duration that thereinforcing fibers must remain in the shaping die 114. Preheating mayalso enable thick sections of reinforcing member to be manufacturedwithout large thermal stresses being created therein due to uneven heatdistribution.

Shaping Die

The preheated impregnated reinforcing fibers (designated as 131 in FIG.16) then proceed to the shaping die 114 to be formed into reinforcingmember. Additional resin material 127 to improve corrosion resistance,add color, provide ultra violet radiation protection, and the like, maybe added at a station 132 at the entrance to the shaping die 114. As theresin material 127 and reinforcing fibers 131 travel through the shapingdie 114, a reinforcing member having a cross-sectional shapecorresponding to the die profile is formed. Exemplary cross-sectionalshapes are illustrated in FIGS. 2, 3, and 5, described above. Theshaping die 114 is also preferably heated. Thus, as the resin material127 and impregnated reinforcing fibers 131 proceed through the shapingdie 114, the resin reacts under the heat and pressure generated by theshaping die, and partially cures.

A number of different methods can be used to position and anchor theshaping die 114 and to apply the heat necessary to initiate the curingreaction of the resin 127. The use of a stationary die frame with a yokearrangement that allows the shaping die 114 to be fastened to the frameis the simplest arrangement. In all die-holding designs, the drag forcethat develops as material is pulled through the shaping die 114 must betransferred to the frame without causing movement of the shaping die orframe deflection. With a yoke arrangement, heating jackets that employhot oil or electrical resistance strip heaters are positioned around theshaping die 114 at desired locations. Thermocouples are also placed inthe shaping die 114 to control the level of heat applied. Multipleindividually-controlled zones can be configured in this manner. Thisapproach is well suited to single cavity set-ups, but becomes morecomplex when the number of shaping dies used simultaneously increase, aseach shaping die requires its own heat source and thermocouple feedbackdevice. Standard heating jackets and heating plates designed toaccommodate multiple shaping dies can be used to help alleviate thislimitation.

Another popular shaping die station configuration uses heated platensthat have fixed zones of heating control with thermocouple feedback fromwithin the platen. The advantage of this method is that all dies can beheated uniformly with reduced-temperature cycling, because changes intemperature are detected early at the source of the heat rather than atthe load. However, a temperature offset will be common between theplaten set point and the actual shaping die temperature. With knowledgeof the differential, an appropriate set point can be established. Theadvantage of quick set-up and replacement of shaping dies stemming fromthe use of heated platens can lead to increased productivity throughreduced down-time, particularly when means for separating the platensautomatically is provided.

A source of cooling water or air should be included in the front of theshaping die 114 at start-up and during temporary shutdown periods toprevent premature gelation of the resin 127. This can be accomplished byusing either a jacket or a self-contained zone within the heatingplaten. Alternatively, the first section of the shaping die 114 can beunheated, and cooling can be accomplished through convection.

A particularly important pultrusion process control parameter is theheating profile of the shaping die 114 because it determines the rate ofthe thermosetting reaction, the position of the reaction within theshaping die, and the magnitude of the peak exotherm. Improperly curedresin may exhibit poor physical and mechanical properties, yet mayappear identical to adequately cured resin. Excess heat input may resultin thermal cracks or crazes, which may destroy the electricalresistance, corrosion resistance, and mechanical properties of thereinforcing member. Heat-sinking zones at the end of the shaping die 114or auxiliary cooling may be necessary to remove heat prior to the exitof the reinforcing member 10 from the shaping die.

Finishing Station

Still referring to FIG. 16, the resin 127 of a formed reinforcing member134 exiting from the shaping die 114 is in a "B" stage. Accordingly, thereinforcing member 134 is in a malleable state as it enters thefinishing station 116. In the finishing station 116, embossing gears orrollers 135 form a non-planar pattern on outer edge portions 136a ofeach flange 136, as illustrated. As described above, the outer edgeportions of each flange may have various patterns and shapes. Inaddition, the embossing gears or rollers 135 may also be utilized topull the reinforcing member 134 through the pultrusion apparatus 110.

Methods of fabricating reinforcing members according to the presentinvention are advantageous because pultrusion can be performed at highrates of speed. Depending on thickness of a reinforcing member,production speeds of between 1 and 10 feet per minute may be achievedvia the present invention.

Reinforcing Member Resin Materials

The resin 127 used to form reinforcing members according to the presentinvention is preferably a thermosetting resin. The term "thermosetting"as used herein refers to resins which irreversibly solidify or "set"when completely cured. Suitable thermosetting resins include unsaturatedpolyester resins, phenolic resins, vinyl ester resins, polyurethanes,and the like, and mixtures and blends thereof. Particularly preferredthermosetting resins are ATLAC™ 31727-00 and POLYLITE™ 31041-00,available from Reichhold Chemicals, Inc., Research Triangle Park, N.C.

Additionally, the thermosetting resins useful in the present inventionmay be mixed or supplemented with other thermosetting or thermoplasticresins. Exemplary supplementary thermosetting resins include epoxies.Exemplary thermoplastic resins include polyvinylacetate,styrene-butadiene copolymers, polymethylmethacrylate, polystyrene,cellulose acetatebutyrate, saturated polyesters, urethane-extendedsaturated polyesters, methacrylate copolymers, polyethyleneterephthalate (PET), and the like in a manner known to one skilled inthe art.

Unsaturated polyester, phenolic and vinyl ester resins are the preferredthermosetting resins of the present invention, such as described in U.S.Pat. No. 5,650,109 to Kaiser et al., the disclosure of which isincorporated herein by reference in its entirety. Suitable unsaturatedpolyester resins include practically any esterification product of apolybasic organic acid or anhydride and a polyhydric alcohol, whereineither the acid or the alcohol, or both, provide the reactive ethylenicunsaturation. Typical unsaturated polyesters are those thermosettingresins made from the esterification of a polyhydric alcohol with anethylenically unsaturated polycarboxylic acid. Examples of usefulethylenically unsaturated polycarboxylic acids include maleic acid,fumaric acid, itaconic acid, dihydromuconic acid and halo and alkylderivatives of such acids and anhydrides, and mixtures thereof.Exemplary polyhydric alcohols include saturated polyhydric alcohols suchas ethylene glycol, 1,3-propanediol, propylene glycol, 1,3-butanediol,1,4-butanediol, 2-ethylbutane-1,4-diol, 1,5-pentanediol, 1,6-hexanediol,1,7-heptanediol, 1,8-octanediol, 1,4-cyclohexanediol,1,4-dimethylolcyclohexane, 2,2-diethylpropane-1,3-diol,2,2-diethylbutane-1,3-diol, 3-methylpentane-1,4-diol,2,2-dimethylpropane-1,3-diol, 4,5-nonanediol, diethylene glycol,triethylene glycol, dipropylene glycol, glycerol, pentaerythritol,erythritol, sorbitol, mannitol, 1,1,1-trimethylolpropane,trimethylolethane, hydrogenated bisphenol-A and the reaction products ofbisphenol-A with ethylene or propylene oxide.

The reinforcing member resin 127 can be formed by the addition ofrecycled PET, such as from soda bottles to the base resin prior topolymerization. PET bottles can be ground and depolymerized in thepresence of a glycol, which produces an oligomer. The oligomer can thenbe added to a polymerization mixture containing polyester monomer andpolymerized with such monomer to an unsaturated polyester.

Unsaturated polyester resins can also be derived from the esterificationof saturated polycarboxylic acid or anhydride with an unsaturatedpolyhydric alcohol. Exemplary saturated polycarboxylic acids includeoxalic acid, malonic acid, succinic acid, methylsuccinic acid,2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, hydroxylsuccinicacid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid,2,2-dimethylglutaric acid, 3,3-dimethylglutaric acid,3,3-diethylglutaric acid, adipic acid, pimelic acid, suberic acid,azelaic acid, sebacic acid, phthalic acid, isophthalic acid,terephthalic acid, tetrachlorophthalic acid, tetrabromophthalic acid,tetrahydrophthalic acid, 1,2-hexahydrophthalic acid,1,3-hexahydrophthalic acid, 1,4-hexahydrophthalic acid,1,1-cyclobutanedicarboxylic acid and trans-1,4-cyclohexanedicarboxylicacid.

Unsaturated polyhydric alcohols which are suitable for reacting with thesaturated polycarboxylic acids include ethylenic unsaturation-containinganalogs of the above saturated alcohols (e.g.,2-butene-1,4-diol).

Suitable phenolic resins include practically any reaction product of aaromatic alcohol with an aldehyde. Exemplary aromatic alcohols includephenol, orthocresol, metacresol, paracresol, Bisphenol A,p-phenylphenol, p-tert-butylphenol, p-tert-amylphenol,p-tert-octylphenol and p-nonylphenol. Exemplary aldehydes includeformaldehyde, acetaldehyde, propionaldehyde, phenylacetaldehyde, andbenzaldehyde. Particularly preferred are the phenolic resins prepared bythe reaction of phenol with formaldehyde.

Suitable vinyl ester resins include practically any reaction product ofan unsaturated polycarboxylic acid or anhydride with an epoxy resin.Exemplary acids and anhydrides include (meth)acrylic acid or anhydride,α-phenylacrylic acid, α-chloroacrylic acid, crotonic acid, mono-methyland mono-ethyl esters of maleic acid or fumaric acid, vinyl acetic acid,cinnamic acid, and the like. Epoxy resins which are useful in thepreparation of the polyvinyl ester are well known and commerciallyavailable. Exemplary epoxies include virtually any reaction product of apolyfunctional halohydrin, such as epichlorohydrin, with a phenol orpolyhydric phenol. Suitable phenols or polyhydric phenols include forexample, resorcinol, tetraphenol ethane, and various bisphenols such asBisphenol-A, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxy biphenyl,4,4'-dihydroxydiphenylmethane, 2,2'-dihydroxydiphenyloxide, and thelike.

Typically, the resin 127 also includes a vinyl monomer in which thethermosetting resin is solubilized. Suitable vinyl monomers includestyrene, vinyl toluene, methyl methacrylate, p-methyl styrene, divinylbenzene, diallyl phthalate and the like. Styrene is the preferred vinylmonomer for solubilizing unsaturated polyester or vinyl ester resins.

The thermosetting resin 127 may be thickened (or B-staged) during themanufacturing process of the reinforcing members. The thickening canoccur before, during, or after passing through the shaping die 114. Theterm "thickened" as used herein relates to an increase in viscosity ofthe resin 127 such that the resin is transformed from a liquid to anondripping paste form. This is often achieved by partial curing orso-called "B-staging" the resin. The term "partial curing" as usedherein refers to incompletely polymerizing the resin 127 by initiatingpolymerization and subsequently arresting the polymerization orcontrolling the polymerization so that full cure occurs at a later time.

Thickening or partial curing is achieved in a variety of ways. Forexample, the thermosetting resin 127 may be thickened by the inclusionof a thickening agent. Suitable thickening agents are commonly known tothose skilled in the art and include crystalline unsaturated polyesters,polyurethanes, alkali earth metal oxides and hydroxides, and polyureas.Often, the thickening agent cooperates with the conditions within ashaping fixture (such as the shaping die 114) to thicken or partiallycure the thermosetting resin 127. The conditions within the fixturewhich are required to effect the thickening or partial cure of thethermosetting resin are dependent upon the thickening agent employed,and are discussed in detail below.

Suitable resins employing a crystalline polyester thickening agent aredescribed in U.S. Pat. No. 3,959,209 to Lake, the disclosure of which isincorporated herein by reference in its entirety. Typically, in anembodiment of the present invention wherein the thermosetting resin 127is thickened with a crystalline polyester, the thermosetting resincomprises a thermosetting resin solubilized in a vinyl monomer. Thecrystalline polyesters useful in the present invention are generallyethylenically unsaturated, and react with the vinyl monomer, althoughone skilled in the art will appreciate that saturated crystallinepolyesters may also be employed.

Methods of preparing crystalline polyester are well known in the art andinclude polyesterifying a symmetrical, aliphatic diol with fumaric acid,lower alkyl esters of fumaric acid, or symmetrical saturated diacidssuch as terephthalic acid, isophthalic acid and sebacic acid. Maleicanhydride or maleic acid or lower alkyl esters of maleic acid may alsobe used in the presence of an appropriate catalyst. Likewise, mixturesof fumaric acid or esters with maleic anhydride or maleic acid or itsesters may also be used. Exemplary crystalline polyesters which may beemployed in the present invention include polyfumarates of1,6-hexanediol, neopentyl glycol, bis-(hydroxyethyl)resorcinol, ethyleneglycol, 1,4-butanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol,or bis-(hydroxyethyl)hydroquinone.

The amount of crystalline polyester added to the thermosetting resin 127will vary depending upon the particular thermosetting resin employed.Typically, about 2 to about 80 percent by weight of crystallinepolyester is required to thicken about 20 to about 98 percent by weightof a thermosetting resin.

The thermosetting resin 127 may also be thickened with polyurethanes.Exemplary thermosetting resin thickened with a polyurethane aredescribed in U.S. Pat. No. 3,886,229 to Hutchinson, the disclosure ofwhich is incorporated herein by reference in its entirety. Typically, inthe embodiment of the invention wherein the thermosetting resin isthickened with a polyurethane, the first resin material comprises athermosetting resin solubilized in a vinyl monomer.

The polyurethanes useful in the present invention typically comprise thereaction product of a polyol and an isocyanate compound. The polyol maybe saturated or unsaturated. Exemplary saturated polyols includeethylene glycol, propylene glycol, butane-1,4-diol, pentane-1,5-diol,hexane-1,6-diol, di(ethylene glycol), and di(propylene glycol). Polymersof glycols may also be employed. Exemplary polymers includepoly(ethylene glycol), poly(propylene glycol), and poly(butylene glycol)and polyols of functionality greater than two, for example, glycerol,pentaerythritol, and trialkylol alkanes, e.g., trimethylol propane,triethylol propane, tributylol propane and oxyalkylated derivatives ofsaid trialkylol alkanes, e.g., oxyethylated trimethylol propane andoxypropylated trimethylol propane.

In an embodiment wherein the thermosetting resin 127 is thickened with apolyurethane including an unsaturated polyol, the unsaturated polyolcrosslinks the urethane groups with the ethylenically unsaturatedpolyester and vinyl monomer of the thermosetting resin. Exemplaryunsaturated polyols include polyesters, and vinyl esters. In oneparticularly preferred embodiment, the unsaturated polyol is a diesterof propoxylated bisphenol-A.

The isocyanate compound employed to produce a polyurethane thickneringagent is typically a polyisocyanate. The polyisocyanate may bealiphatic, cycloaliphatic or aromatic or may contain in the samepolyisocyanate molecule aliphatic and aromatic isocyanate groups,aliphatic and cycloaliphatic isocyanate groups, aliphatic cycloaliphaticand aromatic isocyanate groups or mixtures of any two or morepolyisocyanates.

Exemplary polyisocyanates include 4,4'-diphenylmethane diisocyanate,2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophoronediisocyanates (e.g., 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate), tetramethylene diisocyanate, pentamethylene diisocyanate,hexamethylene diisocyanate and octamethylene diisocyanate, andcycloaliphatic diisocyanates (e.g., 4,4'-dicyclohexylmethanediisocyanate).

The polyurethane may be reacted with the thermosetting resin 127according to any method known to those skilled in the art. The amount ofpolyurethane added to the first resin material will vary depending uponthe particular thermosetting resin employed. Typically, the polyurethanecomprises about 1 to about 60 percent by weight of the thermosettingresin.

The resin 127 may also be thickened using a polyurea thickening agent.Suitable formulation of resins thickened with polyurea are described inU.S. Pat. No. 4,296,020 to Magrans, Jr., the disclosure of which isincorporated herein by reference in its entirety. Typically, in theembodiment of the invention wherein the resin material is thickened withpolyurea, the resin material comprises a resin solubilized in a vinylmonomer. The polyureas useful in the present invention typicallycomprise the product of polyamines with polyisocyanates. Thepolyisocyanates useful in the present invention include those describedabove with reference to urethane thickeners. Aliphatic, cycloaliphaticand aromatic polyamines free of ethylenic saturation are preferredpolyurea precursors in that they form individual polyurea chains whichare relatively cross-linked with the polymer chain formed by thecopolymerization of the ethylenically unsaturated resin and monomers insolution therewith.

Aryl diamines and mixtures thereof such as metaphenylene diamine,paraphenylene diamine, naphthalene diamine, benzidene,bis(4-aminophenyl)methane, 4,4'-diaminodiphenyl sulfone and halogenatedderivatives such as those containing halogen on the benzenoid ring suchas 3,3'-dichlorobenzidine, bis,4-amino-2-chlorophenyl (sulfone),4-bromo-1,3-phenylene diamine, to name a few, are operable.

Low molecular weight aliphatic and cycloaliphatic diamines are alsosuitably employed, such as: ethylene diamine, propylene diamine,hexamethylene diamine, trimethyl hexamethylene diamine, isophoronediamine, 1-amino-3-amino-3,5,5-trimethyl cyclohexane, hydrogenateddi-(aminophenyl)methane, hydrogenated methylene dianiline, diaminomethane, and hydrogenated toluene diamine. The most useful of these arethose that are liquids up to 75EC. For those which are solids underthese conditions, vinyl monomer solutions can be employed to form thehomogeneous mix rapidly. In addition, other suitable amines includepolyoxyalklene polyamines and cyanoalkylated polyoxyalklene polyamineshaving a molecular weight of about 190 to about 2,000 with a preferredrange of about 190 to about 1,000. These amines are prepared accordingto the procedure outlined in a U.S. Pat. No. 4,296,020 to Magrans, Jr.,the disclosure of which is hereby incorporated by reference in itsentirety.

The resin 127 may also be thickened using alkali earth metal oxides orhydroxides. Typical thickeners of this type include calcium andmagnesium oxides or hydroxides. The addition of these components to theresin 127 will transform the liquid thermosetting resin to a semi-solidor solid form. The amount of oxide or hydroxide employed will varydepending upon the particular thermosetting resin 127 employed.Typically, the alkali metal oxide or hydroxide comprises about 1 toabout 15 percent by weight of the first resin material.

The resin 127 also may include an initiator system which cooperates withthe conditions of the shaping die 114 to thicken the resin by partiallycuring the resin. The initiator system may be present in addition to anyof the foregoing thickening agents, or as an alternative thereto.

The initiator system may comprise any number of polymerizationinitiators. Where multiple polymerization initiators are employed, theinitiator system typically comprises polymerization initiators which canbe activated by different conditions. For simplicity, where multiplepolymerization initiators are employed, we refer to the polymerizationinitiator requiring the least activation energy as the "firstpolymerization initiator", and the initiator requiring the mostactivation energy as the "second polymerization initiator". Anypractical number of polymerization initiators having activation energiesbetween the first and second polymerization initiators may also beincorporated into the thermosetting resin matrix. It should not beimplied from the use of the terms "first" and "second" polymerizationinitiator that the invention is restricted to the use of no more thantwo polymerization initiators.

Polymerization initiators which are useful in the practice of thepresent invention typically include free-radical initiators. Typicalfree-radical initiators include peroxy initiators. The reactivity ofsuch initiators is evaluated in terms of the 10 hour half-lifetemperature, that is, the temperature at which the half-life of aperoxide is 10 hours. Suitable first polymerization initiators includepolymerization initiators having a low 10 hour half-life, i.e., a morereactive peroxide initiator, as compared to initiators having a higher10 hour half-life. Suitable second polymerization initiators includepolymerization initiators having a higher 10 hour half-life than the 10hour half-life of the polymerization initiator selected as the firstpolymerization initiator. Exemplary free-radical initiators useful inthe present invention include diacyl peroxides, (e.g., lauroyl peroxideand benzoyl peroxide), dialkylperoxydicarbonates, (e.g.,di(4-tert-butylcyclohexyl) peroxy dicarbonate), tert-alkyl peroxyesters,(e.g., t-butyl perbenzoate), di-(tert-alkyl)peroxyketals, (e.g.,1,1-di-(t-amylperoxy)cyclohexane), di-tert-alkyl peroxides, (e.g.,dicumyl peroxide), azo initiators, (e.g., 2,2'-azobis(isobutyronitrile),ketone peroxides, (e.g., methylethylketone peroxide and hydroperoxides).

In an embodiment wherein the initiator system comprises only onepolymerization initiator, the resin material preferably includes a vinylmonomer. The vinyl monomer and the polymerization initiator may beindependently activated under different conditions thus permitting thepartial polymerization of the resin 127.

The amount of polymerization initiator(s) used is dependent upon thenumber of initiators employed, the conditions at which the selectedinitiators will initiate polymerization, and the time desired forpartial curing. Typically the amount of time desired for partial curingis a short period, i.e., less than 3 hours, and often less than 1 hour.In the embodiment wherein the resin 127 includes only one polymerizationinitiator, the amount of the initiator is typically about 0.1 to about10 percent by weight of the resin. In the embodiment wherein the resin127 includes two polymerization initiators, the amount used is about0.01 to about 4 percent by weight of the first polymerization initiatorand about 0 to about 5 percent by weight of the second polymerizationinitiator based on the weight of the resin 127.

The initiator system and amounts of each polymerization initiatorincorporated into the resin 127 should be such that as the resinimpregnated reinforcing fibers 131 are shaped in the shaping die 114,the conditions therein are sufficient to activate at least one, butpreferably not all polymerization initiators, resulting in the partialpolymerization of the resin 127. Typically, in the embodiment whereinthe initiator system comprises only one polymerization initiator, theresin impregnated reinforcing fibers 131 are shaped through a shapingdie 114 within which the reinforcing fibers 131 are subjected tosufficient heat to activate the polymerization initiator withoutattaining the self-polymerization temperature of the resin 127. In anembodiment wherein multiple polymerization initiators are employed,typically the resin impregnated reinforcing fibers 131 are shaped in theshaping die 114 within which the reinforcing fibers are subjected tosufficient heat to activate at least one, and preferably the first,polymerization initiator to partially cure the resin 127.

The resin 127 may also include other additives commonly employed inresin compositions, the selection of which will be within the skill ofone in the art. For example, the resin material may include reinforcingfillers, particulate fillers, selective reinforcements, thickeners,initiators, mold release agents, catalysts, pigments, flame retardants,and the like, in amounts commonly known to those skilled in the art. Anyinitiator may be a high or a low temperature polymerization initiator,or in certain applications, both may be employed. Catalysts aretypically required in resin compositions thickened with polyurethane.The catalyst promotes the polymerization of NCO groups with OH groups.Suitable catalysts include dibutyl tin dilaurate and stannous octoate.Other commonly known additives which may desirably be incorporated intothe resin material include pigments and flame retardants.

Particulate fillers that can be used with the resin 127 includeinorganic fillers and organic fillers. Exemplary inorganic fillersinclude ceramic, glass, carbon-based inorganic materials such as carbonblack, graphite, and carbonoyl iron, cermet, calcium carbonate, aluminumoxide, silicon dioxide, oxides of nickel, cobalt, iron (ferric andferrous), manganese, and titanium, perlite, talc (hydrous magnesiumsilicate), mica, kaolinite, nitrides of boron and aluminum, carbides ofsilicon, boron, and aluminum, zircon, quartz glass, aluminum hydroxide,gypsum, magnesite, ferrite, molybdinum disulfide, zinc carbonate, andblends thereof. Exemplary organic fillers include aramid andpolyethylene terephthalete. These and other exemplary reinforcingmaterials are described in U.S. Pat. Nos. 4,278,780 to Nishikawa et al.;4,358,522 to Shinohara et al.; 5,011,872 to Latham et al.; 5,234,590 toEtienne et al.; and 4,947,190 to Murayama et al. Preferably, the resin127 includes a ceramic filler; i.e., a material that is the product ofheated earthy raw materials in which silicon with its oxide andsilicates, such as calcium silicate, wollastonite, beryl, mica, talc,and clays such as kaolinite, occupy a predominant position. See Hawley'sCondensed Chemical Dictionary at 240 (11th ed. 1987). A particularlypreferred ceramic filler is KZ Ceramic Powder, a proprietary ceramicpowder available from Ceramic Technologies Corporation, Rowley, Iowa. Inone embodiment, the ceramic filler is advantageously blended with acalcium carbonate filler in a 3:1 blend. The filler can be supplied inmany forms, including powder, fiber, sphere, bead, particle, flake,lamella, and the like.

Reinforcing Fibers

The reinforcing fibers 130, which are impregnated with the resin 127,can comprise up to 75 percent fibers, and preferably comprise at leastbetween about 40 percent and about 70 percent of the reinforcing member134 by weight. The reinforcing fibers 130 are preferably glass fibers.Glass fibers are readily available and low in cost. A typical glassfiber is electrical grade E-glass. E-glass fibers have a tensilestrength of approximately 3450 MPa (practical). Higher tensile strengthscan be accomplished with S-glass fibers having a tensile strength ofapproximately 4600 MPa (practical). The glass fiber can be treated toprovide other properties such as corrosion resistance. Other suitablereinforcing fibers include carbon, metal, high modulus organic fibers(e.g., aromatic polyamides, polybenzimidazoles, and aromaticpolyimides), and other organic fibers (e.g., polyethylene, liquidcrystal and nylon). Blends and hybrids of the various fibers can beused.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. In the claims, means-plus-function clauses are intended tocover the structures described herein as performing the recited functionand not only structural equivalents but also equivalent structures.Therefore, it is to be understood that the foregoing is illustrative ofthe present invention and is not to be construed as limited to thespecific embodiments disclosed, and that modifications to the disclosedembodiments, as well as other embodiments, are intended to be includedwithin the scope of the appended claims. The invention is defined by thefollowing claims, with equivalents of the claims to be included therein.

That which is claimed is:
 1. A concrete reinforcing member comprising:anelongated core defining a longitudinal direction; a plurality ofelongated flanges extending radially outward from said elongated core,each flange having opposite faces terminating at an outer edge; and atleast one slot formed through a portion of said elongated core alongsaid longitudinal direction such that each of said flanges has a freeinner edge adjacent said at least one slot, wherein said concretereinforcing member is bendable along said at least one slot in adirection transverse to said longitudinal direction.
 2. A concretereinforcing member according to claim 1 wherein said flanges areequidistantly spaced around said elongated core.
 3. A concretereinforcing member according to claim 1 wherein said outer edge of eachflange is substantially parallel with said longitudinal direction.
 4. Aconcrete reinforcing member according to claim 1 wherein at least one ofsaid flange faces has a non-planar surface portion for improvingconcrete adhesion thereto.
 5. A concrete reinforcing member according toclaim 1 wherein said elongated core and flanges are formed fromfiber-reinforced resin material.
 6. A concrete reinforcing memberaccording to claim 5 wherein said fibers are unidirectional along saidlongitudinal direction.
 7. A concrete reinforcing member according toclaim 5 wherein said resin material is thermosetting resin.
 8. Aconcrete reinforcing member according to claim 5 wherein said elongatedreinforcing fibers are selected from the group consisting of glass,carbon, metal, aromatic polyamides, polybenzimidazoles, aromaticpolyimides, polyethylene, nylon, and blends and hybrids thereof.
 9. Aconcrete reinforcing member according to claim 5 wherein said fibers arelocated along a face of at least one of said flanges.
 10. A concretereinforcing member according to claim 1 wherein said elongated core hasa cross-sectional dimension less than or equal to a cross-sectionaldimension of any of said flanges.
 11. A concrete reinforcing memberaccording to claim 1 wherein said elongated core has a cross-sectionaldimension between about 0.01 inches and about 1.0 inches.
 12. A concretereinforcing member according to claim 1 wherein said at least one slotcomprises a plurality of slots spaced along said elongated core.
 13. Areinforcing member formed by pultruding reinforcing fibers through a bath of resin material, said reinforcing member comprising:an elongatedcore defining a longitudinal direction; a plurality of elongated flangesextending radially outward from said elongated core, each flange havingopposite faces terminating at an outer edge; and at least one slotformed through a portion of said elongated core along said longitudinaldirection such that each of said flanges has a free inner edge adjacentsaid at least one slot, wherein said reinforcing member is bendablealong said at least one slot in a direction transverse to saidlongitudinal direction.
 14. A reinforcing member according to claim 13wherein said elongated flanges are equidistantly spaced around saidcore.
 15. A reinforcing member according to claim 13 wherein said outeredge of each flange is substantially parallel with said longitudinaldirection.
 16. A reinforcing member according to claim 13 wherein atleast one of said flange faces has a non-planar surface portion forimproving concrete adhesion thereto.
 17. A reinforcing member accordingto claim 13 wherein said resin material is thermosetting resin.
 18. Areinforcing member according to claim 13 wherein said reinforcing fibersare selected from the group consisting of glass, carbon, metal, aromaticpolyamides, polybenzimidazoles, aromatic polyimides, polyethylene,nylon, and blends and hybrids thereof.
 19. A reinforcing memberaccording to claim 13 wherein at least one of said flange edges has alarger cross-sectional dimension than a cross sectional dimension of anyof said flanges.
 20. A reinforcing member according to claim 13 whereinsaid elongated core has a cross-sectional dimension less than or equalto a cross sectional dimension of any of said flanges.
 21. A reinforcingmember according to claim 13 wherein said at least one slot comprises aplurality of slots spaced along said elongated core.
 22. A reinforcedstructure of cementitious material comprising:a mass of cementitiousmaterial; and a reinforcing member formed by pultruding reinforcingfibers through a bath of resin material, said reinforcing membercomprising:an elongated core defining a longitudinal direction; aplurality of elongated flanges extending radially outward from saidelongated core, each flange having opposite faces terminating at anouter edge; and at least one slot formed through a portion of saidelongated core along said longitudinal direction such that each of saidflanges has a free inner edge adjacent said at least one slot, whereinsaid reinforcing member is bendable along said at least one slot in adirection transverse to said longitudinal direction.
 23. A reinforcedstructure according to claim 22 wherein said cementitious materialcomprises Portland Cement.
 24. A reinforced structure according to claim22 wherein said flanges are equidistantly spaced around said elongatedcore.
 25. A reinforced structure according to claim 22 wherein saidouter edge of each flange is substantially parallel with saidlongitudinal direction.
 26. A reinforced structure according to claim 22wherein at least one of said flange faces has a non-planar surfaceportion for improving concrete adhesion thereto.
 27. A reinforcedstructure according to claim 22 wherein said resin material isthermosetting resin.
 28. A reinforced structure according to claim 22wherein said reinforcing fibers are selected from the group consistingof glass, carbon, metal, aromatic polyamides, polybenzimidazoles,aromatic polyimides, polyethylene, nylon, and blends and hybridsthereof.
 29. A reinforced structure according to claim 22 wherein saidreinforcing fibers are located along said face of at least one of saidflanges in contacting relationship with said cementitious material. 30.A reinforced structure according to claim 22 wherein said elongated corehas a cross-sectional dimension less than or equal to a cross sectionaldimension of any of said flanges.
 31. A reinforced structure accordingto claim 22 wherein said at least one slot comprises a plurality ofslots spaced along said elongated core.